Early momentum with two birdies inside five holes was checked with a dropped shot on eight and three putts on the par three 12th saw him lose another stroke.

He focused on claiming birdies on the back nine's two par five holes and admitted he would have been "really happy" with his day had he avoided the dropped shot at the last.

"The greens are firming up, the wind was all over the place, it was a good day at the office," added McIlroy, who forms part of the final group to play on Friday, with a tee time of 18:59 BST.

Augusta day one

Toughest hole: 11 - Par four averaging 4.47 strokes gave up just two of the 250 birdies recorded on day one

Easiest hole: 2 - Par five was torn up at an average of just 4.68 strokes with 40 birdies recorded

Longest driver: Dustin Johnson averaged 305 yards but ended on five over par

Greens in regulation: Bubba Watson hit 16 from 18 and was the only player to end with a bogey-free round

"If conditions stay the same and they put the pin positions in tough spots, it will be tough to get your ball close, so anything even par, one under, two under is a good score.

"I'm feeling good with my game and came in here relaxed to try and enjoy the week. If I can do that and not get ahead of myself then hopefully I'll give myself a great chance."

Holes two and 13, both par fives, played the easiest on the course, with 81 of the day's 250 birdies being claimed on the pair.

England's Lee Westwood, a top-15 finisher in each of the last four years, said he "didn't make enough" of the opportunities the par fives presented after carding a one-over 73.

"That's where you're scoring on this golf course," said Westwood, who was in the day's final group.

"It was a bad draw being out last. You sort of sigh when you see the draw. That's as hard as it will play all day. I will be out a bit earlier on Friday and hopefully it's more scoreable."

Lee Westwood failed to record a birdie on any of Augusta National's par fives on day one of the the Masters

On a day where 19 of the 97-strong field finished under par, England's Justin Rose, winner of the 2013 US Open, finished on four over.

Compatriot Luke Donald finished seven over par having suffered a quadruple bogey on the ninth, where he received a two-shot penalty for grounding his club in the bunker.

"Left my bunker shot in the bunker and touched the sand before my next shot," tweeted Donald, who is yet to win a major. "A pretty dumb mistake.

"I can accept the odd poor shot but making a mistake like that is pretty frustrating and so unlike me. Nothing I can do about it now, brush it off and try and make a bunch of birdies tomorrow."

Meanwhile, England's 19-year-old amateur Matthew Fitzpatrick gave himself "six or seven" out of 10 after shooting a four-over 76 on his Masters debut.

Fitzpatrick pays fairway price

Matthew Fitzpatrick took five fewer putts than McIlroy on day one but only found eight of 18 greens in regulation and consequently finished five shots worse off.

The Sheffield-born player, who qualified as 2013 US amateur champion, was playing with defending champion Adam Scott and said the Australian, who is tied for second with Louis Oosthuizen and Bubba Watson on three under, seemed to have the ball "on a piece of string".

If Fitzpatrick - a Sheffield United fan - makes the cut on Friday, he may well be in action while his team play in the FA Cup semi-final against Hull City on Sunday.

"If you would have said to me last year my soccer team would get to the semi-final of the FA Cup and I'd play at Augusta, I'd just never, ever believe you in a million years," he said.

Scotland's Stephen Gallacher, also a Masters debutant, reached three under at the turn to feature prominently on the leaderboard, but three bogeys in successive holes saw him drop away - eventually finishing on one under.

"I was happy to get under par and stay in the red," said the 39-year-old. "I played with Sandy Lyle, Jose Olazabal and Miguel Angel Jimenez in practice. Their advice was great, you don't go for flags you go for positions."

The Masters 2014

Venue:

Augusta National

Dates:

10-13 April

Coverage:

Live BBC Two coverage on 12 April from 19:30 BST and on 13 April from 18:00 BST. Watch up to seven streams live on mobile, tablet, desktop and selected Connected TVs from 16:00 on 12 and 13 April plus highlights and reaction on 11, 12 and 13 April. Daily live text and radio commentary.